STRUCTURE INCLUDING SiOC LAYER AND METHOD OF FORMING SAME

ABSTRACT

A method for forming a layer comprising SiOC on a substrate is disclosed. An exemplary method includes selectively depositing a layer comprising silicon nitride on the first material relative to the second material and depositing the layer comprising SiOC overlying the layer comprising silicon nitride.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application Ser. No. 62/815,810, filed Mar. 8, 2019 and entitled“STRUCTURE INCLUDING SiOC LAYER AND METHOD OF FORMING SAME,” which ishereby incorporated by reference.

FIELD OF INVENTION

The present disclosure generally relates to methods of formingstructures that include a layer comprising silicon, oxygen, and carbonand to structures including such layers.

BACKGROUND OF THE DISCLOSURE

Silicon nitride films are used for a wide variety of applications. Forexample, such films can be used as insulating layers, as etch stoplayers, and for use in the formation of spacers in the formation ofelectronic devices.

For several applications, it may be desirable to selectively depositsilicon nitride on one material relative to another material. Forexample, it may be desirable to selectively deposit the silicon nitridematerial onto metal relative to dielectric material. Further, because ofsubsequent processing steps, it may be desirable for the silicon nitridematerial to be relatively resistant to wet etching processes, such aswet etching using hydrofluoric acid and/or hot phosphoric acid.

Low pressure chemical vapor deposition (LPCVD) techniques can be used todeposit silicon nitride films with relatively low wet etch rates.However, such films typically require relatively high temperatures fordeposition, and the high temperatures may not be suitable for someapplications. Plasma-enhance chemical vapor deposition (PECVD)techniques have also been used to deposit silicon nitride films;however, films formed using PECVD generally exhibit high wet etch rates.

Low-temperature CVD techniques have been developed for selectivelydepositing silicon nitride films on metal relative to surroundingdielectric. And, atomic layer deposition (ALD) techniques for depositingsilicon nitride have been developed. Such techniques allow fordeposition of films at lower temperatures and ALD has an advantage ofdepositing conformal films. However, the wet etch rates of such filmstend to be relatively high.

Accordingly, improved methods for forming structures, such as structuresincluding silicon nitride films, are desired.

SUMMARY OF THE DISCLOSURE

Various embodiments of the present disclosure relate to methods offorming structures, such as structures suitable for use in themanufacturing of electronic devices. While the ways in which variousembodiments of the present disclosure address drawbacks of prior methodsand structures are discussed in more detail below, in general, variousembodiments of the disclosure provide improved structures that include alayer comprising silicon, oxygen, and carbon, which can be used toobtained desired etch-resistant properties, and to methods of formingsuch structures.

In accordance with at least one embodiment of the disclosure, a methodof forming a structure includes providing a substrate within a reactionchamber, the substrate comprising a surface comprising a first materialand a second material, the first material comprising a metal and thesecond material comprising one or more of an oxide, a nitride, and anoxynitride; selectively depositing a layer comprising silicon nitride onthe first material relative to the second material; and depositing alayer comprising SiOC overlying the layer comprising silicon nitride.The layer comprising SiOC can be used to provide desired wet etchresistance—e.g., during a spacer formation process. In accordance withvarious aspects, the step of selectively depositing includes atomiclayer deposition (ALD). In accordance with further aspects, the step ofselectively depositing can be performed at a relatively low temperature,such as less than 500° C. or between about 100° C. and about 500° C.Exemplary methods can also include a step of exposing the layercomprising silicon nitride to a plasma treatment prior to the step ofdepositing a layer comprising SiOC. The layer comprising SiOC can beformed using thermal or plasma-enhanced ALD The layer including SiOC caninclude SiOCN.

In accordance with additional embodiments of the disclosure, a method offorming a structure includes the steps of: providing a substrate withina reaction chamber, the substrate comprising a surface comprising afirst material and a second material, the first material comprising anoxide and the second material comprising a nitride; and selectivelydepositing a layer comprising SiOC overlying the first material.

In accordance with further exemplary embodiments of the disclosure, astructure includes a layer comprising SiOC. The structure can include aspacer formed using a layer including SiOC. Additionally oralternatively, the structure can include an etch stop cap that is formedfrom a layer including SiOC. The structures can be formed using, forexample, a method as described herein.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of exemplary embodiments of the presentdisclosure can be derived by referring to the detailed description andclaims when considered in connection with the following illustrativefigures.

FIG. 1 illustrates a method of forming a structure in accordance with atleast one embodiment of the disclosure.

FIG. 2 illustrates a structure in accordance with at least oneembodiment of the disclosure.

FIG. 3 illustrates a method of forming a structure in accordance with atleast one embodiment of the disclosure.

FIG. 4 illustrates another structure in accordance with at least oneembodiment of the disclosure.

It will be appreciated that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help improve understanding ofillustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

As used herein, the term “substrate” may refer to any underlyingmaterial or materials that may be used to form, or upon which, a device,a circuit, or a film may be formed. A substrate can include a bulkmaterial, such as silicon (e.g., single-crystal silicon) and can includeone or more layers overlying the bulk material. Further, the substratecan include various topologies, such as recesses, lines, and the likeformed within or on at least a portion of a layer of the substrate.

As used herein, the term “cyclical deposition” may refer to thesequential introduction of precursors (reactants) into a reactionchamber to deposit a layer over a substrate and includes processingtechniques such as atomic layer deposition and cyclical chemical vapordeposition.

As used herein, the term “atomic layer deposition” (ALD) may refer to avapor deposition process in which deposition cycles, typically aplurality of consecutive deposition cycles, are conducted in a processchamber. Generally, during each cycle, a precursor is chemisorbed to adeposition surface (e.g., a substrate surface that can include apreviously deposited material from a previous ALD cycle or othermaterial), forming about a monolayer or sub-monolayer of material thatdoes not readily react with additional precursor (i.e., a self-limitingreaction). Thereafter, in some cases, a reactant (e.g., anotherprecursor or reaction gas) may subsequently be introduced into theprocess chamber for use in converting the chemisorbed precursor to thedesired material on the deposition surface. The reactant can be capableof further reaction with the precursor. Further, purging steps can alsobe utilized during each cycle to remove excess precursor from theprocess chamber and/or remove excess reactant and/or reaction byproductsfrom the process chamber after conversion of the chemisorbed precursor.Further, the term atomic layer deposition, as used herein, is also meantto include processes designated by related terms, such as chemical vaporatomic layer deposition, atomic layer epitaxy (ALE), molecular beamepitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beamepitaxy when performed with alternating pulses of precursor(s)/reactivegas(es), and purge (e.g., inert carrier) gas(es).

As used herein, the term “cyclical chemical vapor deposition” may referto any process wherein a substrate is sequentially exposed to two ormore volatile precursors, which react and/or decompose on a substrate toproduce a desired deposition.

Exemplary embodiments of the disclosure relate to structures thatinclude a layer comprising SiOC. As used herein, unless statedotherwise, SiOC is not intended to limit, restrict, or define thebonding or chemical state, for example, the oxidation state of any ofSi, O, C, and/or any other element in the film. Further, in someembodiments, SiOC thin films may comprise one or more elements inaddition to Si, O, and/or C, such as H or N. In some embodiments, theSiOC films may comprise Si—C bonds and/or Si—O bonds. In someembodiments, the SiOC films may comprise Si—C bonds and Si—O bonds andmay not comprise Si—N bonds. In some embodiments, the SiOC films maycomprise Si—H bonds in addition to Si—C and/or Si—O bonds. In someembodiments, the SiOC films may comprise more Si—O bonds than Si—Cbonds, for example, a ratio of Si—O bonds to Si—C bonds may be fromabout 1:10 to about 10:1. In some embodiments, the SiOC may comprisefrom about 0% to about 50% carbon on an atomic basis. In someembodiments, the SiOC may comprise from about 0.1% to about 40%, fromabout 0.5% to about 30%, from about 1% to about 30%, or from about 5% toabout 20% carbon on an atomic basis. In some embodiments, the SiOC filmsmay comprise from about 0% to about 70% oxygen on an atomic basis. Insome embodiments, the SiOC may comprise from about 10% to about 70%,from about 15% to about 50%, or from about 20% to about 40% oxygen on anatomic basis. In some embodiments, the SiOC films may comprise about 0%to about 50% silicon on an atomic basis. In some embodiments, the SiOCmay comprise from about 10% to about 50%, from about 15% to about 40%,or from about 20% to about 35% silicon on an atomic basis. In someembodiments, the SiOC may comprise from about 0.1% to about 40%, fromabout 0.5% to about 30%, from about 1% to about 30%, or from about 5% toabout 20% hydrogen on an atomic basis. In some embodiments, the SiOCfilms may not comprise nitrogen. In some other embodiments, the SiOCfilms may comprise from about 0% to about 40% nitrogen on an atomicbasis (at %). In some cases, as described in more detail below, thelayer comprising SiOC can be deposited conformally over features on asubstrate and/or can be selectively deposited on one material relativeto another material on a substrate surface.

Turning now to the figures, FIG. 1 illustrates a method 100 of forming astructure in accordance with at least one embodiment of the disclosure.Method 100 includes the steps of providing a substrate within a reactionchamber (step 102), selectively depositing a layer comprising siliconnitride (step 104), and depositing a layer comprising SiOC (step 108).Method 100 also includes an optional treatment step (step 106) that canbe used to treat the silicon nitride deposited during step 104.

During step 102, a substrate is provided into a reaction chamber of areactor. In accordance with examples of the disclosure, the reactionchamber can form part of an atomic layer deposition (ALD) reactor.Exemplary single wafer reactors, suitable for use with method 100,include reactors designed specifically to perform ALD processes, whichare commercially available from ASM International NV (Almere, TheNetherlands). Exemplary suitable batch ALD reactors are alsocommercially available from ASM International NV. Various steps ofmethod 100 can be formed within a single reaction chamber or can beperformed in multiple reactor chambers, such as reaction chambers of acluster tool. Optionally, a reactor including the reaction chamber canbe provided with a heater to activate the reactions by elevating thetemperature of one or more of the substrate and/or thereactants/precursors.

During step 102, the substrate can be brought to a desired temperatureand pressure for deposition of silicon nitride during step 104. By wayof examples, a temperature (e.g., of a substrate or a substrate support)within a reaction chamber can be between about 100° C. and about 500° C.or about 200° C. and about 400° C. A pressure within the reactionchamber can be about 0.5 Torr to about 20 Torr or about 5 Torr to about15 Torr.

In accordance with examples of the disclosure, the substrate providedduring step 102 can include a surface comprising a first material and asecond material, the first material comprising a metal and the secondmaterial comprising one or more of an oxide, a nitride, and anoxynitride. The metal can be or include tungsten; the oxide can be orinclude silicon oxide; the nitride can be or include silicon nitride andthe oxynitride can be or include silicon oxynitride.

During step 104, the layer comprising silicon nitride is selectivelydeposited on the first material (e.g., metal) relative to the secondmaterial (e.g., one or more of an oxide, a nitride, and an oxynitride).An exemplary technique for selectively depositing silicon nitride on thefirst material relative to the second material includes a cyclicaldeposition process, such as an ALD process.

One ALD cycle may comprise exposing the substrate to a first reactant(also referred to herein as a precursor), removing any unreacted firstreactant and reaction byproducts from the reaction space and exposingthe substrate to a second reactant, followed by a second removal step.The first reactant may include, for example, a silicon halide or anothersilicon source. Exemplary silicon halides include silicon tetraiodide(SiI₄), silicon tetrabromide (SiBr₄), silicon tetrachloride (SiCl₄),hexachlorodisilane (Si₂Cl₆), hexaiododisilane (Si₂I₆), octoiodotrisilane(Si₃I₈). The second reactant may comprise a nitrogen source, such asnitrogen gas, ammonia (NH₃), hydrazine (N₂H₄) or an alkyl-hydrazine,wherein the alkyl-hydrazine may refer to a derivative of hydrazine whichmay comprise an alkyl functional group and may also comprise additionalfunctional groups. Non-limiting example embodiments of analkyl-hydrazine may comprise at least one of tertbutylhydrazine(C₄H₉N₂H₃), methylhydrazine (CH₃NHNH₂) or dimethylhydrazine((CH₃)₂N₂NH₂).

During the purge steps, precursors/reactants can be temporally separatedby inert gases, such as argon (Ar) or nitrogen (N₂), to preventgas-phase reactions between reactants and enable self-saturating surfacereactions. In some embodiments, however, the substrate may be moved toseparately contact a first vapor phase reactant and a second vapor phasereactant. Because the reactions can self-saturate, strict temperaturecontrol of the substrates and precise dosage control of the precursorsis not usually required. However, the substrate temperature ispreferably such that an incident gas species does not condense intomonolayers or multimonolayers nor thermally decompose on the surface.Surplus chemicals and reaction byproducts, if any, are removed from thesubstrate surface, such as by purging the reaction space or by movingthe substrate, before the substrate is contacted with the next reactivechemical. Undesired gaseous molecules can be effectively expelled from areaction space with the help of an inert purging gas. A vacuum pump maybe used to assist in the purging.

In some embodiments, exposing the substrate to a silicon halide sourcemay comprise pulsing the silicon precursor over the substrate for a timeperiod of between about 0.5 seconds and about 30 seconds, or betweenabout 0.5 seconds and about 10 seconds, or between about 0.5 seconds andabout 5 seconds. In addition, during the pulsing of the siliconprecursor source over the substrate, the flow rate of the siliconprecursor (e.g., silicon halide) source may be less than 2000 sccm, orless than 1000 sccm, or less than 500 sccm, or less than 250 sccm oreven less than 100 sccm.

In some embodiments, exposing the substrate to the nitrogen source maycomprise pulsing the nitrogen source over the substrate for a timeperiod of between about 0.5 seconds to about 30 seconds, or betweenabout 0.5 seconds to about 10 seconds, or between about 0.5 seconds toabout 5 seconds. During the pulsing of the nitrogen source over thesubstrate, the flow rate of the nitrogen source may be less than 4000sccm, or less than 2000 sccm, or less than 1000 sccm, or even less than250 sccm.

The second vapor phase reactant comprising a nitrogen source may reactwith silicon-containing molecules left on the substrate surface. In someembodiments, the second phase nitrogen source may react with thesilicon-containing molecules left on the substrate surface to deposit asilicon nitride film.

During the purge steps, excess reactant(s) and reaction byproducts, ifany, may be removed from the substrate surface, for example, by apurging gas pulse and/or vacuum generated by a pumping system. Purginggas is preferably any inert gas, such as, without limitation, argon(Ar), nitrogen (N₂) or helium (He). A phase is generally considered toimmediately follow another phase if a purge (i.e., purging gas pulse) orother reactant removal step intervenes.

The cyclical deposition process for forming a silicon nitride film maybe repeated one or more times until the desired thickness of the siliconnitride is achieved. For example, the cyclical deposition processcomprises forming the silicon nitride film with a thickness of betweenapproximately 0.3 nm and approximately 30 nm.

Once an initial desired thickness of the silicon nitride film isdeposited, the silicon nitride film may be exposed to a plasma (step106) in order to improve the material characteristics of the depositedsilicon nitride film, i.e., such as improving the wet etch rate of thesilicon nitride film. The same reaction chamber or separate reactionchambers can be utilized for deposition silicon nitride film and a stepof exposing the layer comprising silicon nitride to a plasma treatment.In embodiments where different reaction chambers are utilized for thecyclical deposition process and the plasma treatment process, thesubstrate may be transferred from a first reaction chamber (for thesilicon nitride film deposition) to a second reaction chamber (for theplasma treatment) without exposure to the ambient atmosphere. In otherwords, methods of the disclosure may comprise forming the siliconnitride film on the substrate by a cyclical deposition process andexposing the silicon nitride film to a plasma utilizing the samesemiconductor processing apparatus. The semiconductor processingapparatus utilized for the cyclical deposition and the plasma treatmentmay comprise a cluster tool which comprises two or more reactionchambers and which may further comprise a transfer chamber through whichthe substrate may be transported between the first reaction chamber andthe second reaction chamber. In some embodiments, the environment withinthe transfer chamber may control, i.e., the temperature, pressure andambient gas, such that the substrate and particularly the siliconnitride are not exposed to the ambient atmosphere. In some embodiments,the reaction chamber configured for exposing the silicon nitride film toa plasma may be configured with a capacitively coupled plasma (CCP)source, an inductively coupled plasma (ICP) source or a remote plasma(RP) source.

During step 106, a source gas from which the plasma is generated maycomprise one or more of nitrogen (N₂), helium (He), hydrogen (H₂) andargon (Ar). In particular embodiments of the disclosure, the source gasfrom which the plasma is generated may comprise a mixture of helium (He)and nitrogen (N₂) and the proportion of helium (He) gas to nitrogen (N₂)gas may be equal, i.e., 50% helium gas (He) to 50% nitrogen gas (N₂)(e.g., about 50:50). In alternate embodiments, the proportion of helium(He) gas to nitrogen (N₂) may be 10%:90%, or 20%:80%, or 30%:70%, or40%:60%, or 60%:40%, or 70%:30%, or 80%:20%, or even 90%:10%.

In some embodiments of the disclosure, exposing the layer comprisingsilicon nitride to a plasma treatment may comprise applying a power tothe plasma source gas(es) of greater than approximately 150 W, orgreater than 300 W, or greater than 600 W, or even greater than 900 W.In addition, the reaction chamber for exposing the layer comprisingsilicon nitride to a plasma treatment may be operated at a reducedpressure, for example, in some embodiments, the reaction chamber forexposing the silicon nitride to a plasma may operate at a pressure ofapproximately less than 4 Torr, or may operate at a pressure ofapproximately less than 2 Torr, or may even operate at a pressure ofapproximately 1 Torr. In some embodiments, the substrate may be heatedduring the plasma treatment process, for example, exposing the siliconnitride film to a plasma may comprise heating the substrate and theassociated silicon nitride film to a temperature of greater thanapproximately 100° C., or to a temperature of greater than approximately200° C., or even to a temperature of greater than approximately 250° C.

In some embodiments of the disclosure, exposing the silicon nitride filmto a plasma comprises exposing the silicon nitride to a plasma for atime period of less than approximately 300 seconds, or for a time periodof less than 150 seconds or even for a time period of less than 90seconds. In certain embodiments of the disclosure, the silicon nitridemay be exposed to the plasma treatment for a longer period of time, forexample, for a time period greater than 2 minutes, or greater than 5minutes, or even greater than 10 minutes. It should be noted that thelonger silicon nitride film is exposed to the plasma, the more likelythat the beneficial effects of the plasma treatment are to saturate, andvery long plasma exposure times may result in damage to the siliconnitride film.

As a non-limiting example embodiment of the disclosure, exposing thesilicon nitride film to a plasma may comprise a helium (He) and nitrogen(N₂) (e.g., about 50%:50%) gas plasma in a reaction chamber comprising acapacitively coupled plasma (CCP) source with a plasma power of 600 W,and a reaction chamber pressure of 2 Torr for a time period of 90seconds.

The plasma treatment may be performed after each silicon nitridedeposition cycle or after a predetermined—e.g., two or more—depositioncycles. The deposition cycles and plasma treatment steps can be repeateda desired number of times until a desired thickness of the siliconnitride is obtained. Further, it may be appreciated that embodiments ofthe disclosure may also include methods wherein the substrate is firstexposed to a plasma treatment step 106 prior to selectively depositingsilicon nitride, step 104. It should also be appreciated that a numberof plasma treatments may be performed in a single complete depositioncycle, as a well as a number of cyclical deposition cycles may beperformed prior to plasma treatment.

After selectively depositing a layer comprising silicon nitride step 104and optional step 106 are complete, a layer comprising SiOC is depositedoverlying the layer comprising silicon nitride during step 108. Thelayer comprising SiOC can be deposited using cyclic deposition, such ascyclic CVD, ALD, or a hybrid CVD-ALD process. Further, such processescan be driven thermally and/or be plasma-enhanced. Step 108 may beperformed in the same or different reaction chamber used during step104. A pressure within the reaction chamber during this step can beabout 0.5 to about 15 Torr or about 1 to about 10 Torr.

In accordance with exemplary embodiments of the disclosure, step 108includes a PEALD process, wherein at least one deposition cycle of thePEALD process includes contacting a surface of the substrate with avapor phase silicon precursor; contacting the adsorbed silicon specieswith at least one reactive species generated by plasma formed from asecond reactant comprising hydrogen; and optionally repeating thecontacting steps until a SiOC film of a desired thickness has beenformed.

In some embodiments, thin SiOC films are formed by repetition of aself-limiting ALD cycle. In some embodiments, for forming SiOC films,each ALD cycle comprises at least two distinct phases. The contactingand removal of a reactant or precursor from the substrate may beconsidered a phase. In a first phase, a vapor phase first reactant orprecursor comprising silicon contacts the substrate and forms no morethan about one monolayer on the substrate surface. This reactant is alsoreferred to herein as “the silicon precursor,” “silicon-containingprecursor,” or “silicon reactant” and may be, for example,bis(triethoxysilyl)ethane (BTESE) or 3-methoxypropyltrimethoxysilane(MPTMS). In some embodiments, excess first vapor phase reactant and anyreaction byproducts are removed from the proximity of the substratesurface. The first vapor phase reactant and any reaction byproducts maybe removed from proximity with the substrate surface with the aid of apurge gas and/or vacuum. Excess reactant and/or reactant byproducts canbe purged as described herein.

In a second phase, a second reactant comprising a reactive speciescontacts the substrate and may convert adsorbed silicon species to SiOC.In some embodiments, the second reactant comprises a hydrogen precursor.In some embodiments, the reactive species comprises an excited species.In some embodiments, the second reactant comprises a species from ahydrogen containing plasma. In some embodiments, the second reactantcomprises hydrogen radicals, hydrogen atoms and/or hydrogen plasma. Thesecond reactant may comprise other species that are not hydrogenprecursors. In some embodiments, the second reactant may comprise aspecies from a noble gas, such as one or more of He, Ne, Ar, Kr, or Xe,for example, as radicals, in plasma form, or in elemental form. Thesereactive species from noble gases do not necessarily contribute materialto the deposited film, but can in, some circumstances, contribute tofilm growth as well as help in the formation and ignition of plasma. Insome embodiments, the reactive species generated from noble gases mayaffect the amount or extent of any damage to the underlying substrate. Askilled artisan will be able to select a noble gas or gases suitable fora particular application. In some embodiments, a gas that is used toform a plasma may flow constantly throughout the deposition process butonly be activated intermittently. In some embodiments, a gas that isused to form a plasma does not comprise oxygen. In some embodiments, theadsorbed silicon precursor is not contacted with a reactive speciesgenerated by a plasma from oxygen. In some embodiments, a secondreactant comprising reactive species is generated in a gas that does notcomprise oxygen. For example, in some embodiments, a second reactant maycomprise a plasma generated in a gas that does not comprise oxygen. Insome embodiments, the second reactant may be generated in a gascomprising less than about 50 atomic % (at %) oxygen, less than about 30at % oxygen, less than about 10 at % oxygen, less than about 5 at %oxygen, less than about 1 at % oxygen, less than about 0.1 at % oxygen,less than about 0.01 at % oxygen, or less than about 0.001 at % oxygen.As noted below, in other embodiments, the second reactant may includeoxygen or another oxidant.

In some embodiments, a gas that is used to form a plasma does notcomprise nitrogen. In some embodiments, the adsorbed silicon precursoris not contacted with a reactive species generated by a plasma fromnitrogen. In some embodiments, a second reactant comprising reactivespecies is generated in a gas that does not comprise nitrogen. Forexample, in some embodiments, a second reactant may comprise a plasmagenerated in a gas that does not comprise nitrogen. However, in someembodiments, a gas that is used to form a plasma may comprise nitrogen.In some other embodiments, the second reactant may comprise nitrogenradicals, nitrogen atoms and/or nitrogen plasma. In some embodiments,the second reactant may be generated in a gas comprising less than about25 atomic % (at %) nitrogen, less than about 20 at % nitrogen, less thanabout 15 at % nitrogen, less than about 10 at % nitrogen, less thanabout 5 at % nitrogen, less than about 1 at % nitrogen, less than about0.1 at % nitrogen, less than about 0.01 at % nitrogen, or less thanabout 0.001 at % nitrogen. In some embodiments, the second reactant maybe generated in a gas comprising hydrogen and nitrogen, for example, thesecond reactant may comprise H₂ and N₂. In some embodiments, the secondreactant may be generated in a gas having a ratio of N₂ to H₂ (N₂/H₂) of(e.g., greater than zero and) less than about 20%, less than about 10%,or less than about 5%.

In some embodiments, a gas that is used to form a plasma does notcomprise nitrogen or oxygen. In some embodiments, the adsorbed siliconprecursor is not contacted with a reactive species generated by a plasmafrom nitrogen or oxygen. In some embodiments, a second reactantcomprising reactive species is generated in a gas that does not comprisenitrogen or oxygen. For example, in some embodiments, a second reactantmay comprise a plasma generated in a gas that does not comprise nitrogenor oxygen. In other cases, the second reactant may include oxygen and/ornitrogen. Excess second reactant and any reaction byproducts can bepurged as described herein.

Additional phases may be added and phases may be removed as desired toadjust the composition of the final film. Further, one or more of thereactants may be provided with the aid of a carrier gas, such as Ar orHe. In some embodiments, the silicon precursor and the second reactantare provided with the aid of a carrier gas.

In some embodiments, two of the phases may overlap, or be combined. Forexample, the silicon precursor and the second reactant may contact thesubstrate simultaneously in phases that partially or completely overlap.In addition, although referred to as the first and second phases, an thefirst and second reactants, the order of the phases may be varied, andan ALD cycle may begin with any one of the phases. That is, unlessspecified otherwise, the reactants can contact the substrate in anyorder, and the process may begin with any of the reactants.

As discussed in more detail below, in some embodiments for depositing aSiOC film, one or more deposition cycles begin by contacting thesubstrate with the silicon precursor, followed by the second precursor.In other embodiments, deposition may begin by contacting the substratewith the second precursor, followed by the silicon precursor.

In some embodiments, if desired, the exposed surfaces of the workpiececan be pretreated to provide reactive sites to react with the firstphase of the ALD process. In some embodiments the substrate ispretreated (e.g., with a plasma) to provide a desired surfacetermination.

A gas can be provided to the reaction chamber continuously during eachdeposition cycle, or during the entire ALD process, and reactive speciescan be provided by generating a plasma in the gas, either in thereaction chamber or upstream of the reaction chamber. In someembodiments the gas does not comprise nitrogen. In some embodiments thegas may comprise noble gas, such as helium or argon. In some embodimentsthe gas is helium. In some embodiments the gas is argon. The flowing gasmay also serve as a purge gas for the first and/or second reactant (orreactive species). For example, flowing argon may serve as a purge gasfor a first silicon precursor and also serve as a second reactant (as asource of reactive species). In some embodiments, argon or helium mayserve as a purge gas for a first precursor and a source of excitedspecies for converting the silicon precursor to the SiOC film. In someembodiments the gas in which the plasma is generated does not comprisenitrogen and the adsorbed silicon precursor is not contacted with areactive species generated by a plasma from nitrogen. In someembodiments the gas in which the plasma is generated does not compriseoxygen and the adsorbed silicon precursor is not contacted with areactive species generated by a plasma from oxygen. In some embodimentsthe gas in which the plasma is generated does not comprise oxygen ornitrogen and the adsorbed silicon precursor is not contacted with areactive species generated by a plasma from oxygen or nitrogen. In othercases, the plasma may contain nitrogen and/or oxygen.

The deposition cycles can be repeated until a film of the desiredthickness and/or composition is obtained. In some embodiments thedeposition parameters, such as the precursor flow rate, contacting time,removal time, and/or reactants themselves, may be varied in one or moredeposition cycles during the ALD process in order to obtain a film withthe desired characteristics.

In some embodiments, the substrate is contacted with the siliconreactant first. After an initial surface termination, if necessary ordesired, the substrate is contacted with a first silicon reactant. Insome embodiments a first silicon reactant pulse is supplied to theworkpiece. In accordance with some embodiments, the first reactant pulsecomprises a carrier gas flow and a volatile silicon species, such asBTESE or MPTMS, that is reactive with the workpiece surfaces ofinterest. Accordingly, the silicon reactant adsorbs upon these workpiecesurfaces. The first reactant pulse self-saturates the workpiece surfaceswith silicon reactant species such that any excess constituents of thefirst reactant pulse do not further react with the molecular layerformed by this process.

The first silicon reactant pulse can be supplied in gaseous form. Thesilicon precursor gas is considered “volatile” for purposes of thepresent description if the species exhibits sufficient vapor pressureunder the process conditions to transport the species to the workpiecein sufficient concentration to saturate exposed surfaces.

In some embodiments the silicon reactant contacts the surface from about0.05 seconds to about 5.0 seconds, about 0.1 seconds to about 3 secondsor about 0.2 seconds to about 1 second. The optimum contacting time canbe readily determined by the skilled artisan based on the particularcircumstances.

After sufficient time for about a molecular layer to adsorb on thesubstrate surface, excess first silicon reactant, and reactionbyproducts, if any, are removed from the substrate surface. In someembodiments, removing excess reactant and reaction byproducts, if any,may comprise purging the reaction chamber. In some embodiments, thereaction chamber may be purged by stopping the flow of the firstreactant while continuing to flow a carrier gas or purge gas for asufficient time to diffuse or purge excess reactants and reactantby-products, if any, from the reaction space. In some embodiments, theexcess first precursor is purged with the aid of inert gas, such ashelium or argon, which is flowing throughout the ALD cycle. In someembodiments, the substrate may be moved from the reaction spacecontaining the first reactant to a second, different reaction space. Insome embodiments, the first reactant is removed for about 0.1 seconds toabout 10 seconds, about 0.3 seconds to about 5 seconds, or about 0.3seconds to about 1 second. Contacting and removal of the siliconreactant can be considered the first or silicon phase of the ALD cycle.

In the second phase, a second reactant comprising a reactive species,such as hydrogen plasma, is provided to the workpiece. Hydrogen plasmamay be formed by generating a plasma in hydrogen in the reaction chamberor upstream of the reaction chamber, for example, by flowing thehydrogen (H₂) through a remote plasma generator.

In some embodiments, plasma is generated in flowing H₂ gas. In someembodiments, H₂ is provided to the reaction chamber before the plasma isignited or hydrogen atoms or radicals are formed. In some embodiments,the H₂ is provided to the reaction chamber continuously and hydrogencontaining plasma, atoms or radicals is created or supplied when needed.

Typically, the second reactant, for example, comprising hydrogen plasma,contacts the substrate for about 0.1 seconds to about 10 seconds. Insome embodiments, the second reactant, such as hydrogen containingplasma, contacts the substrate for about 0.1 seconds to about 10seconds, 0.5 seconds to about 5 seconds or 0.5 seconds to about 2seconds. However, depending on the reactor type, substrate type and itssurface area, the second reactant contacting time may be even higherthan about 10 seconds. In some embodiments, contacting times can be onthe order of minutes. The optimum contacting time can be readilydetermined by the skilled artisan based on the particular circumstances.

In some embodiments, the second reactant is provided in two or moredistinct pulses, without introducing another reactant in between any ofthe two or more pulses. For example, in some embodiments, a plasma, suchas a hydrogen containing plasma, is provided in two or more sequentialpulses, without introducing a Si-precursor in between the sequentialpulses. In some embodiments, during provision of plasma, two or moresequential plasma pulses are generated by providing a plasma dischargefor a first period of time, extinguishing the plasma discharge for asecond period of time, for example, from about 0.1 seconds to about 10seconds, from about 0.5 seconds to about 5 seconds, or from about 1second to about 4 seconds, and exciting it again for a third period oftime before introduction of another precursor or a removal step, such asbefore the Si-precursor or a purge step. Additional pulses of plasma canbe introduced in the same way. In some embodiments, a plasma is ignitedfor an equivalent period of time in each of the pulses.

In some embodiments, plasma, for example, hydrogen containing plasma,may be generated by applying RF power of from about 5 W to about 5000 W,from about 10 W to about 2000 W, from about 50 W to about 1000 W, orfrom about 200 W to about 800 W. In some embodiments, the RF powerdensity may be from about 0.02 W/cm² to about 2.0 W/cm², or from about0.05 W/cm² to about 1.5 W/cm². The RF power may be applied to a secondreactant that flows during the plasma contacting time, that flowscontinuously through the reaction chamber, and/or that flows through aremote plasma generator. Thus, in some embodiments, the plasma isgenerated in situ, while in other embodiments, the plasma is generatedremotely. In some embodiments, a showerhead reactor is utilized andplasma is generated between a susceptor (on top of which the substrateis located) and a showerhead plate. In some embodiments, the gap betweenthe susceptor and showerhead plate is from about 0.1 cm to about 20 cm,from about 0.5 cm to about 5 cm, or from about 0.8 cm to about 3.0 cm.

After a time period sufficient to completely saturate and react thepreviously adsorbed molecular layer of silicon species with the plasmapulse, any excess reactant and reaction byproducts are removed from thesubstrate surface.

In some embodiments, removing excess reactant and reaction byproducts,if any, may comprise purging the reaction chamber. In some embodiments,the reaction chamber may be purged by stopping the flow of the secondreactant while continuing to flow a carrier gas or purge gas for asufficient time to diffuse or purge excess reactants and reactantby-products, if any, from the reaction space. In some embodiments, theexcess second precursor is purged with the aid of inert gas, such ashelium or argon, which is flowing throughout the ALD cycle. In someembodiments, the substrate may be moved from the reaction spacecontaining the second reactant to a different reaction space. Theremoval may, in some embodiments, be from about 0.1 seconds to about 10seconds, about 0.1 seconds to about 4 seconds, or about 0.1 seconds toabout 0.5 seconds. Together, the reactive species contacting and removalrepresent a second, reactive species phase in a SiOC atomic layerdeposition cycle.

The two phases together represent one ALD cycle, which is repeated toform SiOC thin films of a desired thickness. While the ALD cycle isgenerally referred to herein as beginning with the silicon phase, it iscontemplated that in other embodiments, the cycle may begin with thereactive species phase. One of skill in the art will recognize that thefirst precursor phase generally reacts with the termination left by thelast phase in the previous cycle. Thus, while no reactant may bepreviously adsorbed on the substrate surface or present in the reactionspace, if the reactive species phase is the first phase in the first ALDcycle, in subsequent cycles, the reactive species phase will effectivelyfollow the silicon phase. In some embodiments, one or more different ALDcycles are provided in the deposition process.

According to some embodiments of the present disclosure, PEALD reactionsmay be performed at temperatures ranging from about 25° C. to about 700°C., from about 50° C. to about 600° C., from about 100° C. to about 450°C., or from about 200° C. to about 400° C. In some embodiments, theoptimum reactor temperature may be limited by the maximum allowedthermal budget. Therefore, in some embodiments, the reaction temperatureis from about 100° C. to about 300° C. In some applications, the maximumtemperature is around about 200° C., and, therefore the PEALD process isrun at or below that reaction temperature.

A number of different suitable Si precursors can be used in thepresently disclosed PEALD processes. In some embodiments, the suitableSi precursors may not comprise nitrogen. In some embodiments, a suitableSi precursor may comprise a silane.

In some embodiments, a suitable Si precursor may comprise two Si atomsconnected by, or bonded to, at least one hydrocarbon group. In someembodiments, a suitable Si precursor may comprise two Si atoms connectedby, or bonded to, at least one alkyl group. In some embodiments, asuitable Si precursor may comprise two Si atoms connected by, or bondedto, at least one alkoxy group. In some embodiments, a suitable Siprecursor may comprise two Si atoms connected by, or bonded to, at leastone silyl group. In some embodiments, a suitable Si precursor maycomprise two Si atoms connected by, or bonded to, at least one silylether group. In some embodiments, a suitable Si precursor may compriseat least one —SH group, wherein the —SH may be bonded to an alkyl chainor a silicon atom. In some embodiments, a suitable Si precursor maycomprise at least one mercapto group. In some embodiments, a suitable Siprecursor may comprise at least one —R—SH structure, wherein R may be aC₁-C₅ alkyl group. In some embodiments, a suitable Si precursor maycomprise at least one —SH group on an alkyl chain and one or more alkoxygroups bonded to a silicon atom.

In some embodiments, a suitable Si precursor may comprise at least oneSi atom attached or bonded to one or more alkoxy groups. In someembodiments, a suitable Si precursor may comprise at least one Si atomattached or bonded to one or more alkyl groups. In some embodiments, asuitable Si precursor may comprise at least one Si atom attached orbonded to at least an alkyl group and an alkoxy group.

In some embodiments, at least some Si precursors suitable for depositionof SiOC by PEALD processes may comprise bridged alkoxysilanes having thefollowing general formula:

(R^(II)O)₃Si—R^(I)—Si(OR^(II))₃  (1)

wherein each of R^(I) and R^(II) may be independently selected alkylgroups. In some embodiments, each of R^(I) and R^(II) are independentlyselected C₁-C₅ alkyl ligands, such as methyl, ethyl, n-propyl,isopropyl, tertbutyl, or pentyl.

According to some embodiments, some Si precursors may comprise bridgedalkoxyalkylsilanes having the following general formula:

R^(III) _(y)(OR^(II))_(x)Si—R^(I)—Si(OR^(II))_(x)R^(III) _(y)  (2)

wherein each of R^(I), R^(II), and R^(III) may be independently selectedalkyl groups, and x+y=3. In some embodiments, each of R^(I) and R^(II)are independently selected C₁-C₅ alkyl ligands, such as methyl, ethyl,n-propyl, isopropyl, tertbutyl, or pentyl. In some embodiments, R^(III)may be an independently selected C₁-C₈ alkyl ligand.

According to some embodiments, some Si precursors may comprise cyclicalkoxysilanes having the following general formula:

(R^(II)O)₂Si—R^(I) ₂—Si(OR^(II))₂  (3)

Formula (3) may alternately be represented by the structural formula

wherein each of R^(I) and R^(II) may be independently selected alkylgroups. In some embodiments, each of R^(I) and R^(II) are independentlyselected C₁-C₅ alkyl ligands, such as methyl, ethyl, n-propyl,isopropyl, tertbutyl, or pentyl.

According to some embodiments, some Si precursors may comprise cyclicalkoxyalkylsilanes having the following general formula:

R^(III) _(y)(OR^(II))_(x)Si—R^(I) ₂—Si(OR^(II))_(x)R^(III) _(y)  (4)

Formula (4) may alternately be represented by the structural formula

wherein each of R^(I), R^(II), and R^(III) may be independently selectedalkyl groups, and x+y=2. In some embodiments, each of R^(I) and R^(II)are independently selected C₁-C₅ alkyl ligands, such as methyl, ethyl,n-propyl, isopropyl, tertbutyl, or pentyl. In some embodiments, R^(III)may be an independently selected C₁-C₈ alkyl ligand.

According to some embodiments, some Si precursors may comprise linearalkoxysilanes having the following general formula:

(R^(II)O)₃Si—(O—Si—R^(I) ₂)_(n)—O—Si(OR^(II))₃  (5)

wherein R^(I) may be an independently selected alkyl group or hydrogen,R^(II) may be an independently selected alkyl group, and n=1-4. In someembodiments, each of R^(I) and R^(II) are independently selected C₁-C₅alkyl ligands, such as methyl, ethyl, n-propyl, isopropyl, tertbutyl, orpentyl. In some embodiments, R^(I) may be hydrogen and R^(II) may be anindependently selected C₁-C₅ alkyl ligand.

According to some embodiments, some Si precursors may comprise linearalkoxysilanes having the following general formula:

R^(III) _(y)(OR^(II))_(x)Si—(—R^(I)—Si)_(n)—Si(OR^(II))_(x)R^(III)_(y)  (6)

wherein each of R^(I), R^(II), and R^(III) may be independently selectedalkyl groups, x+y=2, and n can be greater than or equal to 1. In someembodiments, R^(I) and R^(II) are independently selected C₁-C₅ alkylligands, such as methyl, ethyl, n-propyl, isopropyl, tertbutyl, orpentyl. In some embodiments, R^(III) may be an independently selectedC₁-C₈ alkyl ligand.

According to some embodiments, some Si precursors may comprisealkoxysilanes having the following general formula:

Si(OR^(I))₄  (7)

wherein R^(I) may be an independently selected alkyl group. In someembodiments, R^(I) may be an independently selected C₁-C₅ alkyl ligand,such as methyl, ethyl, n-propyl, isopropyl, tertbutyl, or pentyl.

According to some embodiments, some Si precursors may comprisealkoxyalkylsilanes having the following general formula:

Si(OR^(I))_(4-x)R^(II) _(x)  (8)

wherein each of R^(I) and R^(II) may be independently selected alkylgroups, and x=1-3. In some embodiments, R^(I) may be an independentlyselected C₁-C₅ alkyl ligand, such as methyl, ethyl, n-propyl, isopropyl,tertbutyl, or pentyl. In some embodiments, R^(II) may be anindependently selected C₁-C₈ alkyl ligand.

According to some embodiments, some Si precursors may comprisealkoxysilanes that do not comprise nitrogen and have the followinggeneral formula:

Si(OR^(I))_(4-x)R^(II) _(x)  (9)

wherein R^(I) may be an independently selected alkyl group, R^(II) maybe any ligand comprising carbon, hydrogen, and/or oxygen that does notcomprise nitrogen, and x=1-3. In some embodiments, R^(I) may be anindependently selected C₁-C₅ alkyl ligand, such as methyl, ethyl,n-propyl, isopropyl, tertbutyl, or pentyl. In some embodiments, R^(II)may comprise, for example, an alkenyl, alkynyl, phenyl, carbonyl,aldehyde, ester, ether, carboxyl, peroxy, hydroperoxy, thiol, acrylate,or methacrylate ligand.

According to some embodiments, some Si precursors may have the followinggeneral formula:

Si(OR^(I))_(4-x)R^(II) _(x)  (10)

wherein x=0-3, R^(I) may be an independently selected C₁-C₇ or C₁-C₅alkyl ligand, and R^(II) may be an independently selected ligandconsisting of carbon, and/or hydrogen, and/or oxygen. For example, insome embodiments, R^(II) can be an alkoxyalkyl group. In someembodiments, R^(II) can be, for example, an alkenyl, alkynyl, phenyl,carbonyl, aldehyde, ester, ether, carboxyl, peroxy, or hydroperoxygroup. In some embodiments, for example, R^(I) is a methyl group, R^(II)is a 3-methoxypropyl ligand, and x is 1.

According to some embodiments, some Si precursors may have the followinggeneral formula:

(R^(I)O)_(4-x)Si—(R^(II)—O—R^(III))_(x)  (11)

wherein x=0-3, each of R^(I) and R^(II) may be an independently selectedC₁-C₇ or C₁-C₅ alkyl ligand, and R^(III) may be an independentlyselected ligand consisting of carbon, and/or hydrogen, and/or oxygen.For example, in some embodiments R^(III) can be, for example, analkenyl, alkynyl, phenyl, carbonyl, aldehyde, ester, ether, carboxyl,peroxy, or hydroperoxy group. In some embodiments, for example, R^(I),R^(II), and R^(III) can each be a group independently selected frommethyl, ethyl, i-propyl, n-propyl, n-butyl, i-butyl, and t-butyl.

According to some embodiments, some Si precursors may have the followinggeneral formula:

Si(R^(I))_(4-x)R^(II) _(x)R^(III) _(y)  (12)

wherein x+y=0-4, R^(I) is an alkoxide ligand having from 1 to 5 carbonatoms, or a halide, R^(II) is any ligand comprising sulfur, and R^(III)consists of one of a sulfhydryl, sulfide, disulfide, sulfinyl, sulfonyl,sulfino, sulfo, thiocyanate, isothiocyanate, or carbonothioylfunctionality. In some embodiments, R^(I), R^(II), and R^(III) may eachbe independently selected. In some embodiments, R^(I) may comprise amethoxy ligand, R^(II) may comprise 3-mercaptopropyl, x=1, and y=0. Thatis, in some embodiments, an Si precursor may comprise Si(OCH₃)₃C₃H₆SH.In some embodiments, a Si precursor may comprisemercaptomethylmethyldiethoxysilane,3-mercaptopropylmethyldimethoxysilane and/or3-mercaptopropyltriethoxysilane.

In some embodiments, the silicon precursor does not comprise a halogen.In some embodiments, the silicon precursor does not comprise nitrogen.In some embodiments, the carbon chain may be unsaturated and containdouble carbon-carbon bonds. In some other embodiments. the carbon chainmay contain other atoms than carbon and hydrogen. According to someembodiments, suitable silicon precursors can include at least compoundshaving any of the general formulas (1) through (11). In someembodiments, the silicon precursor can comprisebis(triethoxysilyl)ethane (BTESE). In some embodiments, the siliconprecursor can comprise 3-methoxypropyltrimethoxysilane (MPTMS orSi(OCH₃)₃C₃H₆OCH₃). In some embodiments, the silicon precursor cancomprise (3-mercaptopropyl)trimethoxysilane.

In some embodiments, more than one silicon precursor may contact thesubstrate surface at the same time during an ALD phase. In someembodiments, the silicon precursor may comprise more than one of thesilicon precursors described herein. In some embodiments, a firstsilicon precursor is used in a first ALD cycle and a second, differentALD precursor is used in a later ALD cycle. In some embodiments,multiple silicon precursors may be used during a single ALD phase, forexample in order to optimize certain properties of the deposited SiOCfilm. In some embodiments, only one silicon precursor may contact thesubstrate during the deposition. In some embodiments, there may only beone silicon precursor and one second reactant or composition of secondreactants in the deposition process. In some embodiments, there is nometal precursor in the deposition process. In some embodiments, thesilicon precursor is not used as a silylating agent. In someembodiments, the deposition temperature and/or the duration of thesilicon precursor contacting step are selected such that the siliconprecursor does not decompose. In some embodiments, the silicon precursormay decompose during the silicon precursor contacting step. In someembodiments, the silicon precursor does not comprise a halogen, such aschlorine or fluorine.

As discussed above, the second reactant for depositing SiOC according tothe present disclosure may comprise a hydrogen precursor, which maycomprise a reactive species. In some embodiments, a reactive speciesincludes, but is not limited to, radicals, plasmas, and/or excited atomsor species. Such reactive species may be generated by, for example,plasma discharge, hot-wire, or other suitable methods. In someembodiments, the reactive species may be generated remotely from thereaction chamber, for example, up-stream from the reaction chamber(“remote plasma”). In some embodiments, the reactive species may begenerated in the reaction chamber, in the direct vicinity of thesubstrate, or directly above the substrate (“direct plasma”).

Suitable plasma compositions of a PEALD process include hydrogenreactive species, that is, plasma, radicals of hydrogen, or atomichydrogen in one form or another. In some embodiments, a second reactantmay comprise a reactive species formed at least in part from H₂. In someembodiments, a plasma may also contain noble gases, such as He, Ne, Ar,Kr and Xe, or Ar or He, in plasma form, as radicals, or in atomic form.

In some embodiments, the second reactant may comprise reactive speciesformed from H₂. In some embodiments, the second reactant may begenerated from a gas containing more than about 25 atomic % (at %)hydrogen, more than about 50 at % hydrogen, more than about 75 at %hydrogen, more than about 85 at % hydrogen, more than about 90 at %hydrogen, more than about 95 at % hydrogen, more than about 96 at %, 97at %, 98 at %, or more than about 99 at % hydrogen.

In accordance with other embodiments of the disclosure, when the layercomprising SiOC comprises SiOCN, the second reactant can comprisenitrogen. For example, the second reactant can include nitrogen oxide(N₂O) or ammonia (NH₃). The SiOCN films can be deposited using thermalor plasma techniques. In the case of thermal deposition, a substratetemperature can be about 200 to about 700 C or about 300 to about 600 Cand a pressure within the reaction chamber can be about 0.5 to about 40or about 5 to about 25 Torr. Further, in accordance with variousexamples of these embodiments, oxygen and/or other oxidants can be usedafter second reactant pulse to reduce the carbon content in the layercomprising SiOCN. In some cases, only a silicon precursor can be used todeposit a layer comprising SiOCN. For example, (tetramethylbis(2,2-dimethylhydrazino)disilane) can be used for thermal depositionof a layer comprising SiOCN without the need of another reactant.

In some embodiments, the gas used to generate reactive species, such asplasma, may consist essentially of hydrogen. Thus, in some embodiments,the second reactant may consist essentially of hydrogen plasma, radicalsof hydrogen, or atomic hydrogen. In some embodiments, the secondreactant may comprise more than about 25 at % hydrogen, more than about50 at % hydrogen, more than about 75 at %, more than about 85 at %, morethan about 90 at %, more than about 95 at %, more than about 96 at %, 97at %, 98 at %, or more than about 99 at % hydrogen plasma, radicals ofhydrogen, or atomic hydrogen. In some embodiments, the second reactantmay be formed, at least in part, from H₂ and one or more other gases,where the H₂ and other gas or gases are provided at a flow ratio(Hz/other gas or gases), from about 1:1000 to about 1000:1 or greater.In some embodiments, the flow ratio (Hz/other gas or gases) may begreater than about 1:1000, greater than about 1:100, greater than about1:50, greater than about 1:20, greater than about 1:10, greater thanabout 1:6, greater than about 1:3, greater than about 1:1, greater thanabout 3:1, greater than about 6:1, greater than about 10:1, greater thanabout 20:1, 50:1, 100:1, or 1000:1 or greater.

In some embodiments, the second reactant does not comprise any speciesgenerated from oxygen. Thus, in some embodiments, reactive species arenot generated from a gas containing oxygen. In some embodiments, asecond reactant comprising reactive species is generated from a gas thatdoes not contain oxygen. For example, in some embodiments, a secondreactant may comprise a plasma generated from a gas that does notcontain oxygen. In some other embodiments, the second reactant may begenerated from a gas containing less than about 50 atomic % (at %)oxygen, less than about 30 at % oxygen, less than about 10 at % oxygen,less than about 5 at % oxygen, less than about 1 at % oxygen, less thanabout 0.1 at % oxygen, less than about 0.01 at % oxygen, or less thanabout 0.001 at % oxygen. In some embodiments, a second reactant does notcomprise O₂, H₂O or O₃. In other embodiments, as described below, thesecond reactant includes an oxidant, such as N₂O, as the secondreactant.

In some embodiments, a hydrogen plasma may be free or substantially freeof oxygen-containing species (e.g., oxygen ions, radicals, atomicoxygen). For example, oxygen-containing gas is not used to generate thehydrogen plasma. In some embodiments, oxygen-containing gas (e.g., O₂gas) is not flowed into the reaction chamber during the hydrogen plasmastep.

In some embodiments, oxygen-containing gas is not used to generate thehydrogen plasma. In some embodiments, oxygen-containing gas (e.g., O₂gas) is not flowed into the reaction chamber during the hydrogen plasmastep.

In some embodiments, the second reactant does not comprise any speciesgenerated from nitrogen. Thus, in some embodiments, reactive species arenot generated from a gas containing nitrogen. In some embodiments, asecond reactant comprising reactive species is generated from a gas thatdoes not contain nitrogen. For example, in some embodiments, a secondreactant may comprise a plasma generated from a gas that does notcontain nitrogen. In some embodiments, the second reactant may begenerated from a gas containing less than about 25 atomic % (at %)nitrogen, less than about 20 at % nitrogen, less than about 15 at %nitrogen, less than about 10 at % nitrogen, less than about 5 at %nitrogen, less than about 1 at % nitrogen, less than about 0.1 at %nitrogen, less than about 0.01 at % nitrogen, or less than about 0.001at % nitrogen. In some embodiments, a second reactant does not compriseN₂, NH₃ or N₂H₄.

In some embodiments, a hydrogen plasma may be free or substantially freeof nitrogen-containing species (e.g., nitrogen ions, radicals, atomicnitrogen). For example, nitrogen-containing gas is not used to generatethe hydrogen plasma. In some embodiments, nitrogen-containing gas (e.g.,N₂ gas) is not flowed into the reaction chamber during the hydrogenplasma step.

However, in some other embodiments, nitrogen reactive species in theform of plasma, radicals of nitrogen, or atomic nitrogen in one form oranother are also provided. Thus, in some embodiments, the secondreactant may comprise reactive species formed from compounds having bothN and H, such as NH₃ and N₂H₄, a mixture of N₂/H₂ or other precursorshaving an N—H bond. In some embodiments, the second reactant may beformed, at least in part, from N₂. In some embodiments, the secondreactant may be formed, at least in part, from H₂ and N₂, where the H₂and N₂ are provided at a flow ratio (H₂/N₂), from about 100:1 to about1:100, from about 20:1 to about 1:20, from about 10:1 to about 1:10,from about 5:1 to about 1:5 and/or from about 2:1 to about 4:1, and insome cases 1:1. For example, a hydrogen-containing plasma for depositingSiOC can be generated using both N₂ and H₂ at one or more ratiosdescribed herein.

In some embodiments, the gas used to generate reactive species, such asplasma, may consist essentially of argon or another noble gas. In someembodiments, a plasma power used for generating a hydrogen-containingplasma can be about 5 Watts (W) to about 5000 W, about 10 W to about2,000 W, about 50 W to about 1000 W, about 100 W to about 1000 W orabout 100 W to about 500 W. In some embodiments, a plasma power used forgenerating a hydrogen-containing plasma can be about 100 W to about 300W. In some embodiments, hydrogen containing plasma may also compriseargon or another noble gas.

In some cases, relatively high power and relatively high pressure can beused during film formation. For example, a power of about 400 W to about800 W or 500 W to about 1000 W or about 700 W at a pressure of about 1Torr to about 15 Torr or about 5 Torr to about 15 Torr or about 9 Torrcan be used to increase conformality and step coverage of the layercomprising SiOC.

FIG. 2 illustrates a structure 200 in accordance with exemplaryembodiments of the disclosure. Structure 200 includes a substrate 202and a feature 203 formed thereon. Feature 203 includes a firstconductive element 204, a second conductive element 206, a third element208, a silicon nitride film 210, and a layer comprising SiOC 212.

Substrate 202 can include any suitable material, include semiconductormaterial and materials typically used to form semiconductor devices. Byway of example, substrate 202 can be or include silicon, other Group IVsemiconductor material, a Group III-V semiconductor, and/or a GroupII-VI semiconductor.

First conductive element 204 can include any suitable conductivematerial. By way of example, first conductive element 204 can be orinclude polysilicon.

Second conductive element 206 can similarly be or include any suitableconductive material. By way of example, second conductive element 206can be or include a metal, such as tungsten or copper.

Third element 208 can be or include any suitable material. By way ofexample, third element 208 can be or include hard mask material, such assilicon nitride or Al₂O₃.

A combination of silicon nitride layer 210 and a layer comprising SiOCcan be used to form a spacer. As noted above, the combination of siliconnitride and the layer comprising SiOC can provide desired selectivity ofsilicon nitride deposition as well as desired wet etch rates.

Turning now to FIG. 3, a method of forming a structure 300 isillustrated. Method 300 includes the steps of providing a substratewithin a reaction chamber (step 302) and selectively depositing a layercomprising SiOC overlying the first material (step 304).

During step 302, the substrate can be brought to a desired temperatureand pressure for deposition of silicon nitride during step 104. By wayof examples, a temperature (e.g., of a substrate or a substrate support)within a reaction chamber can be between about 100° C. and about 500°C., or about 150° C. and about 450° C. A pressure within the reactionchamber can be about 1 to about 30 or about 5 to about 20 Torr.

The substrate can include a surface comprising a first material and asecond material. The first material can include an oxide and the secondmaterial can comprise a nitride. Exemplary oxides include silicon oxide,Al₂O₃ (aluminum oxides). By way of example, a silicon oxide can includethermally-deposited silicon oxide. Exemplary nitrides include siliconnitride, AN (aluminum nitrides). By way of example, the silicon nitridecan be formed using low pressure CVD deposition techniques.

Step 304 can be the same or similar to step 108 described above. Forexample, step 304 can include use of the precursors, temperatures,pressures, and treatment steps described above in connection with step108 and method 100.

FIG. 4 illustrates a structure 400 formed in accordance with exemplaryembodiments of the disclosure. Structure 400 includes a substrate 402,nitride (e.g., silicon nitride) features 404, 406, an oxide (e.g.,silicon oxide) feature 408, and an SiOC cap 410 selectively formed onthe oxide feature, relative to the nitride features. SiOC cap 410 can beused as an etch stop layer. In accordance with exemplary embodiments ofthe disclosure, a thickness of SiOC cap 410 can range from greater than0 to about 100 Å, about 20 to about 75 Å, or about 10 to about 50 Å.SiOC cap layer can be formed of a layer comprising SiOC as describedherein. Further, SiOC cap 410 can be selectively deposited onto oxidefeature 408, with a selectivity greater than about 75, 90, 95, or 99percent.

The example embodiments of the disclosure described above do not limitthe scope of the invention, since these embodiments are merely examplesof the embodiments of the invention, which is defined by the appendedclaims and their legal equivalents. Any equivalent embodiments areintended to be within the scope of this invention. Indeed, variousmodifications of the disclosure, in addition to those shown anddescribed herein, such as alternative useful combinations of theelements described, may become apparent to those skilled in the art fromthe description. Such modifications and embodiments are also intended tofall within the scope of the appended claims.

What is claimed is:
 1. A method of forming a structure, the methodcomprising the steps of: providing a substrate within a reactionchamber, the substrate comprising a surface comprising a first materialand a second material, the first material comprising a metal and thesecond material comprising one or more of an oxide, a nitride, and anoxynitride; selectively depositing a layer comprising silicon nitride onthe first material relative to the second material; and depositing alayer comprising SiOC overlying the layer comprising silicon nitride. 2.The method of claim 1, wherein the step of selectively depositingcomprises atomic layer deposition.
 3. The method of claim 1, wherein atemperature of a susceptor within the reaction chamber during the stepof selectively depositing is between about 100° C. and about 500° C. 4.The method of claim 1, further comprising a step of exposing the layercomprising silicon nitride to a plasma treatment prior to the step ofdepositing a layer comprising SiOC.
 5. The method of claim 4, whereinthe step of exposing the layer comprising silicon nitride to a plasmatreatment comprises exposing the layer comprising silicon nitride to aplasma comprising one or more of nitrogen and helium.
 6. The method ofclaim 4, wherein the step of exposing the layer comprising siliconnitride to a plasma treatment and the step of depositing a layercomprising SiOC are performed within the same reaction chamber.
 7. Themethod of claim 1, wherein the step of depositing a layer comprisingSiOC comprises thermal atomic layer deposition.
 8. The method of claim1, wherein the step of depositing a layer comprising SiOC comprisesplasma-enhanced atomic layer deposition.
 9. The method of claim 8,wherein a power applied during the plasma-enhanced atomic layerdeposition is between about 400 W and about 800 W.
 10. The method ofclaim 8, wherein a pressure within the reaction chamber during theplasma-enhanced atomic layer deposition is between about 5 Torr andabout 15 Torr.
 11. The method of claim 1, wherein the layer comprisingSiOC comprises SiOCN.
 12. The method of claim 1, the step of depositinga layer comprising SiOC comprises providing a precursor comprising oneor more of a methoxysilane, tetramethyl bis (2,2 dimethylhydrazine)disilane and (3-Mercaptopropyl)trimethoxysilane.
 13. A structure formedaccording to the method of claim
 1. 14. The structure of claim 13comprising a spacer.
 15. A method of forming a structure, the methodcomprising the steps of: providing a substrate within a reactionchamber, the substrate comprising a surface comprising a first materialand a second material, the first material comprising an oxide and thesecond material comprising a nitride; and selectively depositing a layercomprising SiOC overlying the first material.
 16. The method of claim15, wherein the step of selectively depositing a layer comprising SiOCcomprises plasma-enhanced atomic layer deposition.
 17. The method ofclaim 16, wherein a power applied during the step of selectivelydepositing a layer comprising SiOC is between about 5 W and about 5000W.
 18. The method of claim 15, wherein a pressure within the reactionchamber during the step of selectively depositing a layer comprisingSiOC is between about 5 Torr and about 15 Torr.
 19. A structure formedaccording to the method of claim
 15. 20. The structure of claim 19,wherein the layer comprising SiOC forms an etch stop cap layer of thestructure.